Recently, environmentally-friendly vehicles such as an electric vehicle using a motor for driving wheels and a hybrid vehicle using a motor and an engine in combination for driving wheels have been of interest. Regarding such a hybrid vehicle, an electric generator mounted on the vehicle is rotated by motive power of the engine, and the generated electric power is used for charging a battery and is also supplied to the motor. Besides these vehicles, a vehicle having an externally chargeable battery that can be charged at home for example (hereinafter simply referred to as external charging) is also under study.
An externally chargeable vehicle may be charged at home for example, and accordingly the frequency at which the vehicle is driven to a service station for fuel replenishment is reduced, which is convenient for drivers. Moreover, electricity at a lower night rate or the like may be used to make the cost reasonable.
Japanese Patent Publication No. 3016349 (Patent Document 1) discloses such an externally chargeable hybrid vehicle.    Patent Document 1: Japanese Patent Publication No. 3016349    Patent Document 2: WO99/61929    Patent Document 3: Japanese Patent Laying-Open No. 2003-7353    Patent Document 4: WO98/56059